Method and apparatus for listening for incoming calls on multiple port/socket combinations

ABSTRACT

In a computer system having a memory, a processor, and a network interface, a method for listening on multiple conferencing interfaces having the steps of loading a set of transport components into the memory; initializing each transport components of the set of transport components to listen on a particular conferencing interface using the network interface, each transport component of the set of transport components listening to a different conferencing interface; receiving an incoming call signal on the network interface having an incoming conferencing interface; processing the incoming call signal to detect the incoming conferencing interface; and launching an application based on the incoming conferencing interface. 
     An apparatus for listening on multiple conferencing interfaces having a set of transport components coupled to the network interface, each transport component of the set of transport components having the capability of receiving a signal on a different conferencing interface; a conference component coupled to each component in the set of transport components; a call processing module coupled to the conference component; and, a process manager coupled to the call processing module; the conference component containing a circuit for causing the call processing module to cause process manager to activate a conferencing application upon detecting a call from one transport component of the set of transport components.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to the field of use of teleconferencingsystems. More particularly, the present invention relates to the dynamiclaunching of teleconferencing applications upon receipt of a call.

2. Description of Related Art

Teleconferencing is increasingly becoming a popular application inpersonal computer systems. Such applications typically allow thetransfer of audio and video data between users so that they can speakand otherwise communicate with one another. Such applications sometimesalso include data sharing wherein various types of data such asdocuments, spreadsheets, graphic data, or other types of data, can beshared and manipulated by all participants in the teleconference.Different teleconference applications perhaps residing on differenthardware platforms have different capabilities. Moreover, a wide varietyof features has been implemented in different teleconferenceapplications, and the proliferation of different types of computersystems with different capacities, and different networking media hascreated challenges for teleconferencing.

For example, most systems which are used for teleconferencingapplications are also used to run such programs for performing wordprocessing, spreadsheet applications, database applications, and avariety of other applications. Thus, the resources contained in thecomputer system are shared between these multiple applications. Often,most computer systems are limited in the amount of random access memorythey contain and also the amount of processing power available forperforming operations. In order for a user to receive calls, the usermust keep the conferencing application open. Otherwise, if the calledparty does not have the conferencing application open, the calling partywould receive a notice that the called party is not present to answerthe call.

So, in order to receive a call, a user currently needs to keep anyconferencing application open. However, keeping the conferencingapplication open is a waste of resources. Memory which is allocated tothe conferencing application could be used for other applications. Also,processing resources are consumed in launching and maintaining theconferencing application. These resources are unnecessarily preoccupiedfor the times when there are no teleconferencing sessions in occurrence.A user can wait until he wishes to initiate a teleconferencing sessionbefore launching the teleconferencing application, but this means thatthere is no call notification unless the user receives a “regular” phonecall, which does not allow for on-demand conferencing.

Thus, a solution needs to be provided that will allow a system todynamically load the conferencing application only when necessary toanswer a call, but not require the conferencing application to be loadedand executing to receive notice of an incoming call.

In addition, a solution should be provided that will allow aconferencing application to wait on incoming calls on various portssimultaneously, thereby allowing a conferencing application which canhandle conferencing over several different network/conferencingprotocols and/or interfaces to achieve parallel conferencingcapabilities (i.e., answering multiple calls, each coming in on adifferent network protocol or a different conferencing interface).

Moreover, a solution needs to be provided for multiple conferencingapplications, each compatible with a different set ofnetwork/conferencing protocols, to be able to listen for incoming callsat the same time.

SUMMARY OF THE INVENTION

The invention provides a method and apparatus for listening on multiplenetwork/conferencing protocols and/or interfaces. In addition, multiplepersistent listening for multiple ports can exist for multipleconferencing applications (i.e., one persistent listen to oneconferencing application) AND for a single conferencing application(i.e., multiple persistent listen to one conferencing application).Thus, for example a conferencing application can listen for incomingcalls on both a TCP/IP port or an AppleTalkl™ port.

The invention can be implemented in a computer system having a memory, aprocessor, and a network interface, a method for dynamically launching aconferencing application upon the receipt of an incoming call comprisingthe steps of loading a set of transport components into the memory;initializing each transport components of the set of transport componentto listen on a particular conferencing interface using the networkinterface, each transport component of the set of transport componentslistening to a different conferencing interface; receiving an incomingcall signal on the network interface having an incoming conferencinginterface; processing the incoming call signal to detect the incomingconferencing interface; and launching an application based on theincoming conferencing interface.

An apparatus including a set of transport components coupled to thenetwork interface, each transport component of the set of transportcomponents having the capability of receiving a signal on a differentconferencing interface; a conference component coupled to each componentin the set of transport components; a call processing module coupled tothe conference component; and, a process manager coupled to the callprocessing module; the conference component containing a circuit forcausing the call processing module to cause process manager to activatea conferencing application upon detecting a call from one transportcomponent of the set of transport components.

The invention will allow a system to dynamically load a conferencingapplication only when necessary to answer a call, but not require theconferencing application to be loaded and executing to receive notice ofan incoming call. In addition, different conferencing applications canalso be “dynamically” launched when incoming calls corresponding to eachdifferent conferencing applications arrive.

Other objects, features and advantages of the invention will be apparentfrom the accompanying drawings, and from the detailed description thatfollows below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an example configuration in which various embodimentsof the invention may be implemented.

FIG. 2 illustrates a single system in which embodiments of the inventionmay be implemented.

FIG. 3 illustrates an example architecture on which a system employingvarious embodiments of the invention is based.

FIG. 4 illustrates a preferences file configured in accordance to theinvention.

FIG. 5 illustrates a system employing various embodiments of theinvention.

FIG. 6 illustrates a system employing various embodiments of theinvention used for initializing persistent listening.

FIG. 7 illustrates a system employing various embodiments of theinvention used for transfering an incoming call.

FIG. 8 is a flow diagram illustrating a prefered operation of theinvention used for dynamically launching a conferencing application.

FIG. 9 illustrates a system employing various embodiments of theinvention used for initializing a second persistent listening.

FIG. 10 illustrates a system employing various embodiments of theinvention used for maintaining a second persistent listening on a secondport.

FIG. 11 illustrates a system employing various embodiments of theinvention used for receiving an incoming call on a first port.

FIG. 12 illustrates a system employing various embodiments of theinvention used for receiving an incoming call on the second port while acall is received on a first port.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides a method and apparatus for dynamicallylaunching teleconferencing applications upon receipt of a call. Forpurposes of explanation, specific embodiments are set forth to provide athorough understanding of the present invention. However, it will beunderstood by one skilled in the art, from reading this disclosure, thatthe invention may be practiced without these details. Further, althoughthe present invention is described through the use of certain specificembodiments thereof, especially, with relation to certain hardwareconfigurations, data structures, packets, method steps, and otherspecific details, these should not be viewed as limiting the presentinvention. Various modifications can be made by one skilled in the art,without departing from the overall spirit and scope of the presentinvention.

A portion of the disclosure of this patent document contains materialwhich is subject to copyright protection. They copyright owner has noobjection to the facsimile reproduction by anyone of the patentdisclosure, as it appears in the Patent and Trademark Office patentfiles or records, but otherwise reserves all copyright rightswhatsoever. Copyright Apple Computer, Inc.

A typical system configuration in which a teleconference may take placeis illustrated as 100 in FIG. 1. For example, a first workstation 150may communicate via teleconference with a second workstation 155, asillustrated. System 150 may include a central processing unit 150 cwhich is coupled to a display 150 d a video input device 150 a, and asound input device 150 b. The system 150 may communicate with oversystem 155 over networking medium 170 via network connection module 160.Network connection module 160 may include any number of network adapterscommercially available such as Ethernet, Token Ring, or any othernetworking standard commercially available. Note that network adapter160 may also include a wireless network adapter which allowstransmission of data between components without a medium 170.Communication is thus provided via network adapter 165 coupled to system155, and bi-directional communications may be established between twosystems. System 150 further has a keyboard 150 e and a pointing device150 f, such as a mouse, track ball, or other device for allowing userselections and user input.

In implemented embodiments of the present invention, a general purposecomputer system is used for implementing the teleconferencingapplications and associated processes to be described here. Althoughcertain of the concepts to be described here will be discussed withreference to teleconferencing, it is apparent that the methods andassociated apparatus can be implemented for other applications, such asfile sharing, real time data acquisition, or other types of applicationswhich sends data from a first participant to a second participant or setof participants. A computer system such as that used for implementingembodiments of the present invention will now be described.

FIG. 2 is a diagram showing a computer system capable of implementingthe present invention, such as a workstation, personal computer or otherprocessing apparatus. The sub-system 300 comprises a bus or othercommunication means 301 for communicating information, and a processor302 coupled with bus 301 for processing information. Sub-system 300further comprises a random access memory (RAM) or other volatile storagedevice 304 (referred to as main memory), coupled to bus 301 for storinginformation and instructions to be executed by processor 302. Mainmemory 304 also may be used for storing temporary variables or otherintermediate information during execution of instructions by processor302. Sub-system 300 also comprises a read only memory (ROM) and/or otherstatic storage device 306 coupled to bus 301 for storing staticinformation and instructions for processor 302, and a mass storagedevice 307 such as a magnetic disk or optical disk and its correspondingdisk drive. Mass storage device 307 is coupled to bus 301 for storinginformation and instructions.

Sub-system 300 may further be coupled to a display 321 such as a cathoderay tube (CRT) or liquid crystal display (LCD) coupled to bus 301 fordisplaying information to a computer user. Such a display 321 mayfurther be coupled to bus 301 for the receipt of video or imageinformation. A keyboard 322, including alphanumeric and other keys mayalso be coupled to bus 301 for communicating information and commandselections to processor 302. An additional user input device is cursorcontrol 323, such as a mouse, a trackball, stylus, or cursor directionkeys, coupled to bus 301 for communicating direction information andcommand selections to processor 302, and for controlling cursor movementon display 321. For teleconferencing applications, system 300 may alsohave coupled to it a sound output device 328, a video input device 329,and sound input device 326, along with the associated D/A(Digital-to-Analog) and A/D (Analog-to-Digital) converters or softwarecodecs for inputting or outputting media signal bitstreams. System 150 cmay further be coupled to communication device 327 which is coupled tonetwork adapter 160 for communicating with other computers over network370.

Note, also, that any or all of the components of system 150 c andassociated hardware may be used in various embodiments, however, it canbe appreciated that any configuration of the system may be used forvarious purposes according to the particular implementation.

In one embodiment, system 300 is one of the Apple Computer® brand familyof personal computers such as the Macintosh 8100 brand personal computermanufactured by Apple Computer, Inc. of Cupertino, Calif. Processor 302may be one of the PowerPC brand microprocessors manufactured byMotorola, Inc. of Schaumburg, Ill.

Although a general purpose computer system has been described, it can beappreciated by one skilled in the art, however, that the followingmethods and apparatus may be implemented in special purpose hardwaredevices, such as discrete logic devices, large scale integrated circuits(LSI's), application-specific integrated circuits (ASIC's), or otherspecialized hardware. The description here has equal application toapparatus having similar function.

FIG. 3 illustrates a plurality of processes and/or apparatus which maybe operative within system 150 c. At the highest level, for example, atthe highest level in the ISO/OSI networking model, a conferencingapplication 401, such as a teleconferencing application, an audio/videoserver, or a data server, communicates with a conference component 400in the form of Application Program Interface (API) calls.

Conference component 400 allows conferencing application 401 toestablish communications between two or more teleconference stations.Control information, and media information can be transmitted betweenthe first participant system and a second participant system. Conferencecomponent 400 communicates with the transport component 402 by sendingmessages for other teleconferencing stations which are encapsulated andplaced into a form that the transport component 402, and the networkcomponent 403, can packetize and transmit over networking medium 170.

Transport component 402 and networking component 403 provide thenecessary operations for communication over the particular type ofnetwork adapter 160 and networking medium 170 according to a particularimplementation. For example, networking component 403 may provide theTCP or ADSP protocols and packetizing, according to those respectivestandards. Transport component 402 can support standards such as H.320or MovieTalk™ transport standards. There can exist multiple transportcomponents and multiple network components, as described below.

The main function of conference component 400 is to establish andmaintain a bi-directional connection between every member of aconference—i.e., between conferencing applications. Conferencingapplications use a control channel to exchange control data that ispertinent to the conference. This data might include user identificationinformation or other information that is germane to the application'soperation. Conferencing applications (e.g., conferencing applications401) define the format and content of these control messages byestablishing their own control protocols within the boundaries of theconferencing API. Conferencing components further establishcommunication channels between a first endpoint and a second endpoint,using underlying transport component 402. Thus, once a media channel hasbeen established, conference component 400 uses the media channel oftransport component 402 which is provided for transmission of media andnon-media information.

Conferencing application 401 controls conference component 400 by theissuance of QuickTime™ Conferencing API calls. Conferencing applicationsoperate using an event-driven model wherein events pertinent to theapplication are issued to conferencing application 401. Conferencingapplication 401 can then take appropriate action either by modifyinginternal data structures within (creating a source or sync), and/orissuance of appropriate messages over the network to other connectedcomponents, or potential participants. In addition, conferencecomponents also respond to events and messages that are received. Inaddition, conference components take appropriate actions pertaining tothe receipt of API calls from conferencing applications.

There can exist multiple conferencing components, wherein eachconferencing application requires at least one conference component, buteach conferencing application can have more than one associatedconference component. Each conferencing component has an uniqueidentification number. In addition, each conference component containsone “listen string”, which is unique. A listen string is theencapsulation of the parameters of the “MTConferenceListen” API call foreach conference component. Listen strings can contain more than onenetwork or port. A listen string is composed of two parts: a fixedportion identifying a service name (which is similar to service namesgiven to printers in an AppleTalk™ network that are displayed in theChooser application in the Apple Macintosh operating system), and avariable portion containing a list of one or more service types, whichcontain the transport/network types with which the transport componentsand network components can interface. For example, service types can beport numbers for TCP/IP networks or device types for AppleTalk network.The transport/network tuples will be described below in association withthe discussion of FIG. 5.

The system as shown in FIG. 3 requires that a conferencing application401 be present to handle incoming call events generated by conferencecomponent 400. As conferencing applications (such as conferencingapplication 401) utilize significant system resources (e.g., processorprocessing power and memory space), the requirement that conferencingapplication 401 be executing even when there are no calls present tonecessitate the existence of a conferencing application prevents the useof those resources by other applications. A system that removes therequirement by allowing conferencing application 401 to be launched whenneeded (i.e., launching only when there is an incoming call to handle),is described below.

FIG. 5 illustrates a preferred embodiment of the invention having a calldirector 502; a demon conference component 504 (i.e., a conferencecomponent acting in demon mode); a transport component 506; and anetwork component 508. The preferred embodiment also contains a calldirector preferences 510. Call director 502, demon conference component504, transport component 506, and network component 508 can be referredto as call processing module.

Call director 502 is a “faceless” background process that is loaded atinitialization of the computer system contained in FIG. 2. One of themain functions of call director 502 is to initiate the automaticlaunching of a conferencing application when a call is received by thecomputer system. In addition, call director 502 is responsible forinitiating and interacting with demon conference component 504 tocontrol the transfer of calls to a conferencing application. As afaceless process—i.e., a process that does not need to contain any codeto interface directly with a user—call director 502 requires very littlein terms of system resources. More importantly, aside from theindications given by the dynamic launching capabilities and otherfunctionality provided by call director 502, and the relatively smallmemory foot-print of call director 502, the user does not even have tobe aware that call director 502 is existent. Through the use of theelements contained in FIG. 5, conferencing application 401 does not haveto be loaded and executing until an incoming call exists.

Demon conference component 504, which is controlled by call director 502through the use of the QuickTime™ Conferencing Application API, isresponsible for performing the persistent listening for incoming calls.Demon conference component 504 is created by call director 504 aftercall director 504 has finished launching. Demon conference component 504is an instance of the class of conference components that is initiatedinto a special mode of operation by call direction 504 through the useof a “MTConferenceSetPersistence” API call with the parameter“mtPersistenceDemonMode”.

In a preferred embodiment, there can only be one demon conferencecomponent in each computer system. Demon conference component 504 is theonly conference component instance of call director 502. That is, calldirector 502 can only have a single instance of a conference component(as opposed to conferencing application, which can have multipleconference component instances). Demon conference component 504communicates with other conference components to transfer incoming callsindicated by transport component 506 and network component 508 using ashared data structure in memory. A preferred embodiment of the shareddata structure is further described below, along with a description ofthe basic operations of the invention, while referencing FIG. 6.

FIG. 6 illustrates a sample configuration using the preferred embodimentof the invention wherein conferencing application 401 and conferencecomponent 400 interacts with call director 502 and demon conferencecomponent 504 through the use of a shared queue structure 512.

Inter-Conference Component Communication

In the preferred embodiment, conference components communicate (i.e.,achieve interprocess communication) through the use of shared memory.Specifically, conference components communicate through the use ofglobally accessible data structures composed of a demon queue and anapplication queue, both of which are contained in shared queue structure512. The demon queue is used by any conferencing component of aconferencing application to send commands and information to demonconferencing component 504 (“QdPersistenceOn”, “QdPersistenceOff”,“QdListenAgain”, “QdPersistenceClear”). The application queue is used bythe demon conferencing component to send messages to other conferencingcomponents (“QdListenerStatus”, “QdDemonOff”, “QdIncomingCall”). It isto be noted that the choice of using queues to allow inter-componentcommunication is not intended to be limiting, and other methods ofallowing inter-component communication can be used to achieve the samefunctionality. For example, instead of using queues to transfer commandsand information, messages can be passed from one conferencing componentto another. Alternatively, registers may be used to pass informationfrom one conference component to another.

In the following description of FIG. 6, it is assumed that call director502 has been loaded at the time of initialization of the computersystem, and call director 502 has created an instance of the class ofconference components and initialized into that conference componentinstance into demon conference component 504 through the use of the“MTConferenceSetPersistence” API call with a parameter of“mtPersistenceDemonMode”. It is important that a demon conferencecomponent such as demon conference component 504 exists so as to performpersistent listening. If there is not a conference component in demonmode, there can be no persistent listening. Moreover, if a conferencingapplication tries to turn on persistent listening when there is no demonconference component initiated, the conference component of theconferencing application will return a “mtDemonKaputErr” message,indicating that there is no demon conference component to turn-onpersistent listening.

Setting-Up Persistent Listening

As stated above, demon conference component 504 is responsible forlistening for incoming calls on behalf of all conferencing applicationsthat request persistent listening. Call director 502 is responsible fordynamically launching (if necessary) and transferring an incoming callto the conferencing application which requested persistent listening.The process for configuring demon conference component 504 and calldirector 502 in the preferred embodiment is as follows:

(1) conferencing application 401 will first send an“MTConferenceSetPersistence” API command with an “mtPersistenceOnMode”parameter after being launched to conference component 400;

(2) conference application 401 will then send an API command(“MTConferenceListen”) requesting persistent listening and passing alisten string, which includes the identification of the port on which itwishes demon conference component 504 to listen, to conferencingcomponent 400;

(3) conference component 400 will place a request (QdPersistenceOn) onthe demon queue to have demon conference component 504 performpersistent listening on the port specified by conferencing application401 (the request containing an application signature, as discussedbelow, identifying conferencing application 401 as the requester and theparameters, or so-called “listen string”, of the listening thatconferencing application 401 is requesting, the parameters including aservice name and a port);

(4) demon conference component 504 will initialize transport component506 and network component 508 as necessary to perform persistentlistening on the requested service type and port;

(5) at substantially the same time as step (4), demon conferencecomponent 504 will also notify call director 502 through the use of a“mtPersistenceChangedEvent” that conferencing application 401 hasrequested persistent listening, and send the application signature ofconferencing application 401 and the listen string, which, as stated,includes information regarding the service type and port on whichconferencing application 401 wishes to listen;

(6) call director 502 will then store the information received fromdemon conference component 504, including the application signature ofconferencing application 401 (call director 502 will create an alias, asdescribed below, for conferencing application 401 from the applicationsignature), the service name, the transport type, the network type, andthe service type into call director preferences 510; and,

(7) lastly, conferencing application 401 can either end execution orremain running—but under either case, the listening for incoming callswill be done by demon conference component 504, as described below.

Persistent Listening of Incoming Calls

During normal operations, demon conference component 504, afterdetecting an incoming call, will notify the conferencing applicationwhich requested the listening to transfer the incoming call. Asmentioned above, in order to ensure that an incoming call can bematched-up with a conferencing application, call director 502 uses calldirector preferences 510 to track of the conferencing applications thatrequests persistent listening. Call director 502 also uses call directorpreferences 510 to track all listen strings of the various conferencecomponents corresponding to the various conferencing applications. Alsoas discussed above, each listen string corresponds to a particularconference component and contain the service and the ports for whichthat conference component is responsible. Thus, call directorpreferences 510 contains: (1) a list of aliases for conferencingapplications that requested listening; and (2) what each conferencingapplications want to listen on, such as the name of a user, thetransport and the network type, and the service type (e.g., a portnumber for TCP/IP)).

FIG. 4 illustrates the contents of call director preferences 510,displayed in content window 410, containing logical representations of:a listen strings list 412 (“mtls”), and a conferencing application aliaslist 414 (“alis”). Call director 502 uses call director preferences 510to keep track of the persistent listening requests of conferencingapplications, and to hold the values used to initiate a demon conferencecomponents (e.g., demon conference component 504), any transportcomponents (e.g., transport component 506), and any network components(e.g., network component 508). The contents of listen strings list 412is displayed in a listen string list window 416. The contents ofconferencing application alias list 414 is displayed in alias listwindow 418.

As can be seen in listen string list window 416, only one listen string,a listen string 420, is contained in listen strings list 412. Listenstring 420 is identified in listen string list 412 by the uniqueidentification number “20556”, which is the identification number usedto identify related resources in call director preferences 510. Inaddition, in listen string list window 416, it is shown that listenstring 420 was initialized by conferencing application 401, which inthis example is entitled “QuickTime™ Web Conference”. Thus, listenstring 420 identifies that conference component 400 belongs toconferencing application 401.

The contents of listen string 420 is displayed in a listen stringcontent window 422. Listen string 420 contains a service name 424(“James Watt” in ASCII and a hexadecimal equivalent), a transport type426 (“mtlktcpi” in ASCII and a hexadecimal equivalent), and a port 428(“458” in ASCII and a hexadecimal equivalent). Thus, conferencingcomponent 401 is the requester of persistent listening for transporttype 426 and port 428.

Referring still to FIG. 4, a conferencing application alias 430 is shownin conferencing application alias list 414 in alias list window 418.Conferencing application alias 422 has an identification number 20556,which is the same identification number used to identify listen string420 in call director preferences 510. Conferencing application alias 422is used by call director 502 to locate and launch conferencingapplication 401 (i.e., QuickTime™ Web Conference) when an incoming callmatches the profile contained in listen string 420. The aliasescontained in conferencing application alias list 414 is kept in calldirector preferences 510 and only used by call director 502—i.e. aliasesare never passed down to demon conference component 504.

The contents of conferencing application alias 430 is shown in aliascontent window 432 and contains the location of conferencing application401.

Answering of Incoming Calls After Persistent Listening Has BeenActivated

After persistent listening has been set-up, assuming that conferencingapplication is still running (see FIG. 6), when an incoming call isdetected by transport component 506, demon conference component 504 willtransfer the incoming call to conferencing component 400, which willnotify conferencing application 401 of the incoming call. The incomingcall is transferred through the following sequence:

(1) demon conference component 504 sends a “QdIncomingCall” message toconference component 400 through the use of shared queue structure 512;

(2) conference component 400 creates a new instance of a transportcomponent and a new instance of a network component, which in FIG. 7 istransport component 402 and network component 403, respectively;

(3) demon conference component 504 sends conference component 400 areference to transport component 506;

(4) conference component 400 “answers” the call by sending a“MTTransportAnswer” message, along with the reference to transportcomponent 506, to transport component 402 instance to transfer the callfrom transport component 506;

(5) after the call has been transferred successfully, conferencecomponent 400 sends a “QdListenAgain” message to demon conferencecomponent 504 through the use of shared queue structure 512; and,

(6) demon conference component 504 issues a “TTransportListen” API callto transport component 506 to await the next incoming call.

System Re-Initialization After Persistent Listening has been Initialized

When the computer system is re-initialized and call director 502 isloaded and begins execution after system initialization, the followingstart-up sequence occurs:

(1) call director 502 reads call director preferences 510 and retrievesany listen strings;

(2) call director 502 initializes demon conference component 504 toplace it into demon mode as described above;

(3) call director 502 sends one “MTConferenceDemonListen” API call todemon conference component 504 for each listen string that is retrievedfrom call director preferences 510, where each API call passes demonconference component 504 the retrieved listen string and the associatedapplication signature for the conferencing application that requestedthe listening.

Hi-jacking of Listening

A later conferencing application will replace the listening ofconferencing application 401 if the later conferencing application wantsto listen to the same port (under TCP/IP) or the same name/device (underAppleTalk). If this occurs, a “mtListenHijackedErr”, generated by demonconference component 504, will be received by conference component 400if conferencing application 401, which has been “hi-jacked,” is stillrunning. Conference component 400 will then inform conferencingapplication 401 that the listening requested by conference component 401has been taken over so that conferencing application 401 can take anynecessary action.

In addition, demon conference component 504 will send a“MTConferenceSetPersistence” API call with the parameter of“mtPersistenceOffMode”, along with the application signature ofconferencing application 401, to call director 502. Call director 502will then remove the listen strings for conferencing application 401from call director preferences 510.

If conferencing application 401 is not running when a hi-jack occurs,then the “mtListenHijackedErr” will be removed after a certain time.

Turning Off Persistent Listening

If persistent listening is turned off for a listen string (i.e., aconference component), there will be no notification of incoming callsfor that listen string if the conferencing applications that handlesthat listen string is not loaded and executing—i.e., the system willoperate as it had before the existence of the invention. However, theuser will continue to receive notification of incoming calls on thelisten strings for which persistent listening has not been turned off.

The sequence to turn off persistent listening will depend on whetherconferencing application 401 is loaded and executing. If conferencingapplication 401 is loaded and executing, then the sequence is asfollows:

(1) conferencing application 401 sends conference component 400 arequest to turn off persistent listening via a“MTConferenceSetPersistence” API call with “mtPersistenceOffMode”parameter;

(2) conference component 400 sends a “QdPersistenceOff” message to demonconference component 504;

(3) demon conference component 504 will then remove transport component506 and network component 508 and send a “QdDemonOff” message toconference component 400;

(4) demon conference component 504 sends a “MTPersistenceChangedEvent”message to call director 502 with the application signature forconferencing application 401;

(5) call director 502 removes the listen string for conference component400 from call director preference 510;

(6) conference component 400, after receiving the “QdPersistenceOff”message from demon conference component 504, will create a new instanceof a transport component and a new instance of a network component andinitialize them for local listening—i.e. conference component 400 willbe responsible for waiting for an incoming call for the listen string.

If the user thereafter quits conferencing application 401, then thesystem will operate as if call director 502 is not present and the userwill receive no notifications of incoming calls as conferencingapplication is not loaded and executed to perform listening.

It is to be noted that as a listen string can have more than onetransport component and network component created for persistentlistening—e.g., a listen string contains the listening for both a TCP/IPport and a AppleTalk service—demon conference component 504 will have toremove all the transport components and network components associatedwith the listen string for which persistent listening is turned off instep (3). In addition, when those instances of transport components andnetwork components are removed, the conference component which requeststhat persistence listening be turned off for its listen string (e.g.,conference component 400) will have to create a new set of transportcomponent and network component instances to continue listening in step(6).

For a user to turn off persistent listening for the services and portthat conferencing application 401 processes if conferencing application401 is not currently loaded and executing, the user has to first launchconferencing application 401. Conferencing application 401 then readsits own preference files and performs listen with same values as it didthe last time it executed (i.e., conference component 400 sends a listenrequest with the same listen string it sent to initiate persistentlistening to demon conference component 504). Then, the same sequenceused to turn off persistent listening is used, as described above.

Dynamic Launching of a Conferencing Application

FIG. 8 is a flow diagram of the preferred operation of the inventionwherein call director 502 operates to dynamically launch a conferencingapplication after persistent listening has been initialized and anincoming call is received. The system in operation at the start of theflow diagram is as shown in FIG. 5.

In block 802, call director 502 detects an incoming call through the useof demon conference component 504 and transport component 506. Calldirector 502 is notified by an “mtIncomingCallForEvent”, containing anapplication signature of the conferencing application which set-up thelisten string.

In block 804, demon conferencing component 504 will place a“QdIncomingCall” message on the application queue with the applicationsignature, listen string, identity of transport component 506 (i.e., areference to transport component 506), and an “MTAddress” parameter,which identifies the address of the caller. Demon conference component504 will also send an “MTIncomingCallForEvent” to call director 502 thatan incoming call has been received along with an application signatureand listen string for conferencing application 401 and conferencecomponent 400. Call director 502 then checks the current process list tosee if the conferencing application with the target applicationsignature (i.e., conferencing application 401) is a process that iscurrently running. Operation will then continue with block 806, asdiscussed below. If the conferencing application is not running, calldirector 502 will try to launch the conferencing application, asdiscussed in block 808.

In block 808, where the conferencing application is not currentlyexecuting, call director 502 will determine if the conferencingapplication is locatable so that it can be launched—i.e., whether thelocation of the conferencing application can be ascertained. Calldirector 502 will retrieve conferencing application alias 422 forconferencing application 401 from call director preferences 510, updatethe location of conferencing application 401 if necessary, and then usethe process manager to launch conferencing application 401. If aconferencing application corresponding to conferencing application alias422 cannot be found (e.g., where conferencing application 401 has beenremoved from the storage devices accessible to the computer system),then operations will continue with block 824.

In block 810, if conferencing application is locatable, call director502 will determine whether there is enough free memory to run theconferencing application. If there is enough memory for conferencingapplication 401 to execute, call director 502 will then initiate thelaunching of conferencing application 401 continuing with block 812.

If there does not exist enough memory for the conferencing applicationto execute, operations will continue with block 816, where the user willbe notified through an alert dialog that conferencing application 401does not have enough memory to launch, and unless the user terminatesand quits one or more processes that are currently occupying memory, theuser will not be able to accept the incoming call. Call director 502will keep checking for the user to free up memory until a predeterminedtime-out period has elapsed in block 818. At the end of the time-outperiod, if the user has not freed-up enough memory, operation willcontinue with block 826. If the user does free up enough memory, theoperations will continue with block 812.

In block 812, where there exists enough memory for conferencingapplication 401 to begin execution, call director 502 will launchconferencing application 401 by using the process manager. Conferencingapplication 401 is notified that it must process the incoming call andtherefore launches.

After conferencing application 401 has launched, the systemconfiguration will be as shown in FIG. 6, where conferencing application401 and its associated conference component 400 has loaded and isexecuting.

In block 814, call director 502 checks to see if conferencingapplication 401 is listening in the same way as it was when theconferencing application set-up call director 502 for persistentlistening. If conferencing application 401 does not listen in the sameway within a reasonable time, demon conference component 504 recognizesthat the incoming call has not been handled (i.e., the incoming callevent has not been removed from the application queue) and will informcall director 502 with a “mtPersistenceChangedEvent” with the“mtPersistenceOffMode” parameter and the application signature ofconferencing application 401. Call director 502 will then remove theentry for conferencing application 401 from call director preferencefile 510 in block 824, as described below. If conferencing application401 is listening in the same way, then conferencing application 401 istransferred the incoming call as in block 806.

In block 806, and referring to FIG. 7, after the conferencingapplication has completed launching, or if the conferencing applicationis already executed, call director 502 will transfer the incoming callto the conferencing application, as described above, and return tolistening, as discussed in block 822, below.

After conferencing application 401 has been transferred the call,conferencing application 401 will then be responsible for giving theuser an option to accept the call. If the user decides to accept thecall, then conferencing application 401 will perform as usual an processthe incoming call. If the user does not accept the call, then operationwill continue with block 820. It is to be noted that whether or not theuser decides to accept the call, call director 502 is not affected aftercall director 502 has transferred the incoming call to conferencingapplication 401 and returns to listening, as discussed in block 822.

In block 822, after either: (1) call director 502 has transferred theincoming call to the conferencing application as in block 806; or (2)demon conference component 504 has dropped the call—i.e. removed thecall from the incoming call event queue—as in block 826, demonconference component 504 will return to listening.

In block 824, where conferencing application 401 is not locatable orconferencing application 401 is not listening using the same values withwhich conferencing application 401 set-up call director 502, calldirector 502 will remove all references to conferencing application 401from call director preferences 510.

In block 826, if there is not enough memory available to launchconferencing application 401 and the user does not free-up any memorywithin the time-out period in block 816, then the incoming call will notbe answered and the caller will receive a notice that the user thecaller is trying to contact is not available. The incoming call willalso be dropped if conferencing application 401 is not listening in thesame way as it was when conferencing application 401 set-up calldirector 502 to listen for incoming calls. If there is not enough memoryavailable to launch conferencing application 401 and the user does notfree-up any memory within the time-out period in block 816, then thesystem will be the one shown in FIG. 5, where conferencing application401 and conference component 400 are not executing. If conferencingapplication 401 is not listening in the same way as it was whenconferencing application 401 set-up call director 502 to listen forincoming calls, then the system will be as shown in FIG. 6, whereconferencing application 401 and conference component 400 are executingeven though they are not processing any incoming calls.

Listening on Multiple Ports By Multiple Conferencing Applications

FIG. 9 illustrates a preferred embodiment of the invention forinitiating persistent listening on multiple ports where the system ofFIG. 6 (wherein conferencing application 401 and conference component400 has set-up persistent listening, as discussed above) now includes asecond conferencing application 518 and a second conference component520. Second conferencing application 518 and second conference component520 is launched and initiated the same way as conferencing application401 and conference component 400.

It will be recalled that in the discussion of FIG. 6, transportcomponent 506 and network component 508 have been initialized to listenfor an incoming call matching the parameters of the listen stringbelonging to conferencing application 401. Now, in FIG. 9, secondconferencing application 518 wishes to set-up persistent listening undera different set of parameters (e.g. under AppleTalk, versus TCP/IP forconferencing application 401). The sequence followed by secondconferencing application 518 is identical to the sequence performed byconferencing application 401, except for the different value of thelisten string passed to demon conference component 504 and call director502 to set-up a different transport component and a different networkcomponent.

In FIG. 9, before second conferencing application 518 has requested andset-up persistent listening, there is only persistent listening beingperformed for conferencing application 401. After second conferencingapplication 518 has set-up persistent listening, the system will be asshown in FIG. 10.

In FIG. 10, after second conferencing application 518 has set-uppersistent listening, a second transport component 514 instance and asecond network component 516 instance has been created to perform thelistening requested by second conferencing application 518. Secondtransport component 514 and second network component 516 are identicalto transport component 506 and network component 508, except that theyare set-up to listen for incoming calls having the parameters of thelisten string of second conference component 520.

In FIG. 11, an incoming call has come in matching the parameters of thelisten string for conference component 400 and demon conferencecomponent has transferred the incoming call to conferencing 401, asdiscussed above.

In FIG. 12, while conferencing application 401 is processing theincoming call received in FIG. 11, an incoming call has come in forsecond conferencing application 518 and has been transferred to secondconferencing application 518 through the creation of a third transportcomponent 522 and a third network component 524 to

Thus, the explanation give above in FIGS. 5-8 can be modified bysubstituting second conferencing application 518, second conferencecomponent 520, third transport component 522, third network component524, second transport component 514 and second network component 516 forconferencing application 401, conference component 400, transportcomponent 402, network component 403, transport component 506 andnetwork component 508, respectively, with the exception that there wouldnow be a different listen string for second conference component 520. Inaddition, listen strings list 412 and conferencing application aliaslist 414 in FIG. 4 would contain an additional listen string for secondconference component 518 and an additional alias for second conferencingapplication 520, respectively. For example, if second conferencingapplication 518 is not loaded when an incoming call matching theparameters of the listening requested by second conferencing application518 came in, then second conferencing application 518 and secondconference component 520 would be dynamically launched to handle theincoming call as discussed in FIG. 8.

It is to be noted that not only can persistent listening for multipleports can exist for multiple conferencing applications, multiplepersistent listening can exist for a single conferencing application ifthere is more than one service in the listen string of the conferencecomponent of that conferencing application, as mentioned above.

While the present invention has been particularly described withreference to the various figures, it should be understood that thefigures are for illustration only and should not be taken as limitingthe scope of the invention. Many changes and modifications may be madeto the invention, by one having ordinary skill in the art, withoutdeparting from the spirit and scope of the invention.

What is claimed is:
 1. In a computer system having a memory, aprocessor, and a network interface, an apparatus comprising: means forloading a set of transport components into said memory; means forinitializing each transport component of said set of transportcomponents to listen on a particular conferencing interface using alisten string to associate with said network interface, each transportcomponent of said set of transport components listening to a differentconferencing interface, said listen string encapsulating the parametersto one or more calls to listen; means for receiving an incoming callsignal on said network interface having an incoming conferencinginterface; means for processing said incoming call signal to detect saidincoming conferencing interface; and means for launching an applicationbased on said incoming conferencing interface.
 2. The apparatus of claim1, further comprising: meaning for receiving an initialization messagefrom said application; and means for removing said application from alist if said initialization message does not correspond to an expectedmessage.
 3. The apparatus of claim 1, wherein said means for processingsaid incoming call signal comprises: means for receiving a signal from aresponding transport component in said set of transport components;means for determining an identification of said responding transportcomponent; and means for deriving said incoming conferencing interfaceusing said identification of said responding transport component.
 4. Theapparatus of claim 1, wherein said means for launching said applicationcomprises: means for determining an application signature for saidapplication based on said incoming conferencing interface; means forlocating said application using said application signature; and meansfor signaling a process manager to launch said application.
 5. Theapparatus of claim 1, wherein said conferencing interface comprises atransport control protocol/internet protocol port.
 6. The apparatus ofclaim 1, wherein said conferencing interface comprises an AppleTalkport.
 7. The apparatus of claim 1, further comprising: means for using alisten string to set up a demon conference component to performpersistent listening for incoming calls on behalf of all conferencingapplications that request persistent listening.